The New Zealand Educational Institute (NZEI) says it "would not be surprised" if the Ministry of Education sought an injunction to stop the proposed teachers strike.

More than 500 members of NZEI, the largest education union in the country, voted on Wednesday to strike in February because of the ministry's proposed overhaul of Christchurch schools.

However, because industrial action is only legal in the case of collective agreement disputes or health and safety issues, the strike has been deemed by some as "unlawful", including NZEI president Ian Leckie.

Kathryn Dalziel, an employment law specialist and partner at Christchurch law firm Taylor Shaw, said the ministry could seek an intervention from the court if the strike did not fall under one of those categories.

"The short answer is that they get a declaration that it's unlawful, and as the employer they can challenge the lawfulness of the strike."

Dalziel said it could be "an interesting test for the New Zealand law system".

"Because it doesn't appear that they're (the NZEI) bargaining for a collective process it appears that they will try and bring the strike under health and safety. And my initial reaction is that it's going to be a long bow to draw."

Leckie said he would not be surprised if the ministry sought to stop the strike in the courts.

"If the ministry seeks an injunction well then so be it."

He would not comment on the action the union would take if faced with an injunction.

The Minister of Education, Hekia Parata, said she was "disappointed to hear that the union has chosen this course of action.

"I am also disappointed with their claim that we have not consulted with the profession. We had two rounds of community engagement before the proposals were announced. The consultation period is nearly twice as long as is required and I personally visited 36 of the most affected schools and heard from parents, teachers, children and wider school communities - there has been ample time for the profession to have input."

A ministry spokesman said it was in discussions with NZEI and did not want to "pre-empt" the outcome.

Meanwhile, Christchurch union members are amping up their campaign to be heard.

Parkview School teacher John Leadbetter said they were working with the NZEI to rally support and raise awareness for the strike. Fliers, brochures and advertisements would be used to spread the word.

"We're working on a campaign to inform the parents, the community and to inform New Zealand. Basically, we're trying to get across the reasons we're doing it."